327 Not Breathing Right?!?!

[Slick67]

I need some of you breather gurus to check this out for me. The oilfiller cap popped off from the crankcase pressure. It WAS routed to the PVC on the manifold, but now I know that was incorrect. I realize that the PVC needs to be replaced with a 90 fitting to the brake booster, but where can I get enough vacuum with no holes in the valve covers???? The engine is a fresh engine that has not been broke in yet so this also adds to the equation. Longhorn Man, chime in!!!

[chev-obsession]

Where i drew the arrow, there is a 1.375" hole that used to have an old drain pipe connected to it, (it is now clearly capped off, and very common on old blocks). And you have valve covers with no holes for a breather or a PCV, but you do have a breather on the front of the intake.

So it looks to me like you need to either put the old drain pipe back on, or get some valve covers with holes for a breather and PCV

[AustinScott]

either one of the "large" ports at the base of the carb should be fine.

my 327 has ALOT of crankcase pressure aka "blowby" so I have to run 2 PCV valves into my carb,
one on the front port and one on the back port.
If I don't I get oil out of the breather on the valve cover, even with baffled ports.

[Slick67]

I could not find any indication that there was a hole on the back of the block. My goal is to keep the valve covers clean, but not at the expense of issues with the engine running properly. If I run the hose from the breather cap to the PCV in the manifold and another Tee'd off to the carb base plate would that be an option?

[406 Q-ship]

There has to be points for crankcase venting to work. Your set up there is really only one. In the original set up for an early 265/283/327 the hole back by the distributor is where the "road draft tube" would go and on the later PCV vehicles it would have an oil seperator that had a hose run to the air cleaner. The PCV valve screwed into the oil fill tube on the front with a non-vented oil cap. Look at the way the later valve cover systems work, one side is fresh air pull from the air cleaner (or filter air) and the other side is has the PCV valve placed in the valve cover and the hose attached to a full manifold vacuum source. You need a place for filter air to replace the fumes being pulled by the PCV system or your going to have oil leak problems in after awhile.

[rsavage]

Where you have the arrow, there should be a hole in the block for a special fitting that a hose attached to for pc valve to carb base. I have one that I'll take a photo of later this morning. There was also a canister that bolted inside the lifter gallery which kept oil from being sucked up from the gallery.

[Slick67]

So without the road draft tube the only other option is to ventilate the valve covers and run the vacuum lines as usual?

[Livrat]

Originally Posted by Slick67

So without the road draft tube the only other option is to ventilate the valve covers and run the vacuum lines as usual?

Correct...

[Slick67]

One of these on the back end of each valve cover should cure my issue. And will look pretty slick while maintaining the integrity of the factory script valve covers that I am running. The hole should be drilled as high as possible on the vc's to allow for inertia oil movement upon acceleration.
http://www.summitracing.com/parts/SUM-440332/

[Slick67]

Kinda strange, but there is absolutely no signs of the block even being machined in that area from the factory. The casting numbers show it is a 1966 Corvette block so it may have never had one to begin with.

[rsavage]

Here's what I was talking about. Someone must have put an inch and a quarter freeze plug in your block where this went?

[chevykevy]

Check out PMC valve covers. They look like the old school chevrolet but have holes in the side so you can vent and use a pcv valve. They are cast aluminum with the chevrolet script.

[Slick67]

Originally Posted by Hubscrub

here is a pic of the back of the block with the thingy in it and check out this threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=366853

This is toooo cool and I would not mind that at all...........but, I don't have the hole for the thingy in my block. The block is solid there and has not been filled in. I actually found that thread while researching this problem and wanted to look at it again...Thanks!!!

Originally Posted by chevykevy

Check out PMC valve covers. They look like the old school chevrolet but have holes in the side so you can vent and use a pcv valve. They are cast aluminum with the chevrolet script.

Couldn't find the PMC valve covers, do you have a url? They sound cool and I would like to check into them.

[Slick67]

I gotta keep these valve covers if I can simply because I think they just look super cool. I hate to drill in the back of them, but it is for the greater good of the engine.

[NGN]

I thought the set-up in the pic that 'rsavage' showed were used up to 1967 on 283 & 327, so why would a 1966 motor not have the hole unless there was something different with the Corvette motors like, maybe it was once a fuel injection factory set-up. But that's now going way out of my league.

[Slick67]

Way outta my league too. In the end if the engine breaths right I'll be happy. I have some valve covers with holes in them so I am going to try those on to see if it makes a huge difference. It should. I will post pics of what I am trying before I tap holes into the valve covers I am using.

[77chris03]

try some nasal strips.....that should get her breathin right....haha

[Slick67]

Originally Posted by 77chris03

try some nasal strips.....that should get her breathin right....haha

Funny guy huh! She sounds alot better than she did. Routed the oil filler to the carb, the power booster to the manifold and the trans to the front of the carb on the small tube. It seems to be fine now, we'll see after I run it a little bit.

[Hubscrub]

i hope it works out i love the look of those valve covers on it

[Slick67]

Originally Posted by Hubscrub

i hope it works out i love the look of those valve covers on it

Thanks dude! I think they look right at home on it too. No holes is even better.

[fleetsidelarry]

Originally Posted by Slick67

Routed the oil filler to the carb, the power booster to the manifold and the trans to the front of the carb on the small tube. It seems to be fine now, we'll see after I run it a little bit.

Slick67, love that engine, it is sharp!

I'm a little confused, unless I'm reading the above wrong, you ran the filler tube cap to one of the large carb "vacuum" sources and swapped the booster to the manifold source. also you're now running the tranny off one of the smaller carb sources.

If that's the case, as far as your crankcase ventilation goes, I don't see where you changed anything. And if you now have the tranny hooked to the passenger side port on the front of the carb it is no longer getting a vacuum signal at idle.

it appears to me you are still pulling a low pressure on the crankcase with no cross ventilation.

Sorry, I may be missing something

[Slick67]

Originally Posted by fleetsidelarry

Slick67, love that engine, it is sharp!

I'm a little confused, unless I'm reading the above wrong, you ran the filler tube cap to one of the large carb "vacuum" sources and swapped the booster to the manifold source. also you're now running the tranny off one of the smaller carb sources.

If that's the case, as far as your crankcase ventilation goes, I don't see where you changed anything. And if you now have the tranny hooked to the passenger side port on the front of the carb it is no longer getting a vacuum signal at idle.

it appears to me you are still pulling a low pressure on the crankcase with no cross ventilation.

Sorry, I may be missing something

Thanks! The trans is going to be hooked to the small driver side tube on the front of the carb. The booster is hooked to the manifold, which is correct according to other vehicles. But I am still questioning the ventilation also. There should be a entrance for fresh air, correct?

[cdowns]

valve covers cool?

without a proper PVC system the old school result was SLUDGE heavy thick and grimey NOT COOL

[Slick67]

Originally Posted by cdowns

valve covers cool?

without a proper PVC system the old school result was SLUDGE heavy thick and grimey NOT COOL

I will cut them if needed to avoid the sludge issue. If I do this, it has to be exactly what the engine needs. Holes in the vc's is a major step that I do not want to make a mistake on.

[LONGHAIR]

The real issue here is that you are not allowing "incoming" air. You have the oil filler tube connected to vacuum, which will produce a vacuum inside the crank case. If you do not have some kind of filtered way to let air in, it will suck in a gasket somewhere. Must likely it will be one of the intake end seals or valve cover gaskets.
The whole point of the PVC system is that it does indeed draw out fumes, but it has another tube connected to the air cleaner to allow air in from the other side. That's the bigger heater hose sized tube that goes to the stock air cleaner housing. Most times when the stock unit is removed, a simple vent is installed in place of that tube.

If you want to keep the valve covers un-touched, you are going to have to find an alternative way to let air in. You could drill and tap a hole near the back of the intake manifold, behind the runners, that would get to the lifter valley. This would allow you to put a hose on it, allowing a "remote" breather. It's not an ideal thing because the intake air and PVC draw would both be in the lifter valley. It probably wouldn't pull fumes from the valve covers as well as the "correct" set-up, but it will eliminate the gasket sucking problem.